1. Field of the Invention
The present invention relates to nondestructive, quantitative determination of the three-dimensional distribution of the defects in single crystals.
2. Description of the Related Art
Characterization of the orientations and locations of dislocation lines in single crystals, together with the Burgers vectors, is an important issue not only for identifying the nature of dislocations but also for understanding the formation of local microstructure (lattice tilt, strain etc).
Quantitative determination of the three-dimensional distribution of the structural defects except dislocations is also necessary to identify the nature of defects and understand the formation of local microstructure.
Some X-ray topographic techniques, such as stereographic techniques in Laue (Lang, 1959a,b; Haruta, 1965) or Bragg (Vreeland, 1976) geometries, and the ‘topo-tomographic’ technique (Ludwig et al., 2001), are currently applied for qualitative determination of the orientations and locations of dislocation lines.
In the stereographic techniques such as Laue, and Bragg, white beam x-rays are used and photographic x-ray film is used to obtain Laue spots. From various Laue spots, some topographs are obtained by optical microscope with magnification. By comparing images of defects on the topographs, mainly topographs of different reflections, the distribution of defects is determined qualitatively.
Accordingly, the conventional techniques provide approximation on distribution of defects. They also require off-line processing work such as film development, etc.
In a topo-tomographic technique, the basic principle is 3-D reconstruction of defects from a thousand images of defects obtained by topographic rotation method. A monochromatic beam together with transmission geometry is used. However, the topo-tomographic technique requires that a special type of sample, for example, a small piece of sample or a stripe type of sample, appropriate for 360 degrees rotation of the sample, is required. This topo-tomographic technique is thus not applicable to a wafer type of sample. In addition, this technique needs a lot of time in performing a long data processing including a reconstruction work. Nevertheless, it may only provide qualitative information on distribution of defects.
On the other hand, recent developments of on-line high-resolution diffraction imaging, activated by using real-time imaging systems in conjunction with synchrotron radiation (Koch et al., 1998), have significantly facilitated the mapping of local microstructure by rocking curve imaging (Lübbert et al., 2000).
A straightforward correction between the local microstructure and the configuration of the dislocations involved is an issue of interest. For this work, the dislocation characterization that is experimentally compatible with the rocking curve imaging is required.